Two-stroke engine



July 10, 1923. 1.461.348

'R. H. DICKINSON TWOSTROKE ENGINE Filed Nov. 2'7 1920 a Sheets-Sheet 1 Julflo, 1923.

R. H. DICKINSON TWOSTROKE ENGINE s Sheets-$heet 5 Filed Nov. 27 l920 FIGS %ZJYF Patented July 10, 1923,

RICHARD HARLAND DICKINSON, OF FARNHAIVT, ENGLAND.

TWO-STROKE ENGINE.

A pplication filed November 27, 1920. I Serial No. 426,729.

To all whom it may concern:

Be it known that I, RICHARD HARLAND DIoKiNsoN, a subject of the King of England, residing at Farnhamfin the county of Surrey, England, have invented certain new and useful Improvements in Two-Stroke Engines, of which the. following is a specification. I

This invention relates to internal combustion engines designed to work on a twostroke cycle.

The improved engine'is of the type in are employed, one end of the cylinder serving for the induction and partial compression of the chargevand the other end for the further compression, the explosion and expansion of the gases.

According to the present invention, the

working cylinder which is provided at the head end with a mechanically operated exhaust valve,'is provided also towards its opposite end for the admission of the work ing charge with a transfer port communi cating'with the inlet port at this end, both these ports openingdirectly into a chamber containing the charge-inlet valve which is preferably mechanically operated. The exhaust valve is opened towards the 'end of the expansion stroke and before the piston uncovers the transfer port, and at the head end of the cylinder there may be provided a sparkingplug or other meansof ignition. r

V The charge induced into and initially compressed in the crank end of the cylinder is preferably of pure air, andthe transfer of this compressed air serves to scavenge the working end of the cylinder in the known manner whilst the exhaust valve remains open. Fuel is then injected above the'piston through an orifice in the cylinder wall and forms with the air therein the ex plosive mixture which is finally compressedand exploded. The injection of fuel is preferably efiected by a mechanical pump arranged in ajconstant-levelfuel reservoir in proximity to the fuel-in ection orifice, as

grooves provided upon the crank discs.

The invention'is hereafter described with reference to the accompanying drawings in Figure 1 is an end elevation of'a single cylinder engine. 1 I

Figure2 is a longitudinal section of the same. i 1 Figure 3 is a face view of one of the crank c ISCS.

Figure 4 is a detail in section on a larger scale of the preferredform of fuel injection pump. p which one or more double-ended cylinders;

Figure '5 is The cylinder at isprovided at its head end a with anexhaust valve 7) communicating I with exhaust manifold b and a sparking plug 0, while the crank end a of the cylinder is provided with an induction port a and a transfer port a which communicate with a chamber a contain ng an inlet valve cl. The piston e is of such depth as to bridge the web separating the ports a a, so that in the position shownin Figure 2 there is afree passage from beneath the piston "through the induction port 0, into the inlet valve chamber w" and thence through "the transfer port a? into'the cylinder above the piston.

A fuel injectionorifice f is arranged in the cylinder wall above the transfer port,

fuel'beingdelivered through this orifice by a pump 9 from the reservoir '72, after the piston has covered the transfer porta in its upward movement.

The piston e is provided with a packing.

rings 6 and is formed integral with a-rod '6 connected at its lower end to a dummy piston or cross-head z' reciprocating in a 1 working cylinder" a. "A cover-j is secured between the cylinders, and carries a-central gland j to prevent leakage around the-p sguide cylinder y' co-axially aligned with the 1 ton rod. This gland is shown in Figureyfifl as comprising two halves contracted by springs" j andv having interengaging fingers i at their abuttingjfaces. The crosshead is fitted with a gudgeon pin i on which is mounted the connecting rod 70, of

which the big-end 70' engages the .crank pin Z. In theconstruction illustrated a built-upcrank-shaft is shown consisting of discs: or internal flywheels m secured upon axles m rotating in suitable bearings n in the sides of the crank case 0, the crank pin Z connecting together the two crank discs on.

The discs m are provided on'their outer faces (see Figure 3) with cam grooves m which receive the roller-fitted extremities p of the valve tappets 79 moving in guides p and serving to operate the valves 2) (Z. The tappets are preferably adjustable and may be connected to the valve-stems b d by means 01": spring coils 79 so as to close the valvesmechanically. Springs Z) (Z of the usual type may however be provided to close the valves, either instead of or in addition to the positive connections between valves and tappets.

The inlet valve tappet has a pro ecting spur p operating a push rod 9' of which the upper end engages in a rocker arm 9 adapted to depress the fuel injection pump plunger G These parts may also be positively connected for example by ball or knuckle joints, so that the pump plunger is raised by the return of the inlet tappet,

or a spring may be employed to raise the plunger.

The cam groove m upon the inlet valve side is timed to open the inlet valve (Z to allow the ingress of fresh air through the opening (Z in the side wall of the engine as soon as the rising piston e covers the transfer port at, and since the fuel pump is operated by the same cam-groove, the in ection of fuel will take place approximately at the same moment. The inlet valve closes as the piston reaches the upper end of its stroke, thereby allowing the fuel pump plunger to rise and take in a fresh charge in prepara tion for the next injection. The amount of this charge may be adjusted by a needle-valve 9* controlling the port throughwhich the liquid enters from the reservoir in, in which it is maintained at constant level by a float h carrying a valve 72/ serving to regulate the supply from a pipe h The liquid delivered by the pump passes through a non-return valve f in the pipe or chamber leading to the injection port 7 where it emerges into the cylinder through a suitable nozzle or sprayer.

The cam-groove m upon the opposite crank-discis timed to open the exhaust valve Z) before the piston c uncovers the in ection orifice f, so'that the exhaust has already beigun when the transfer port 66418 uncovered.

The air compressed beneath the piston then passes through the transfer port and com.- pletes the scavenging of the gases replacing them by acharge of air. The exhaust valve Z) closes as he piston rises to the level of the upper edge of the transfer port, at approxi- "mately the same momentas the inlet valve d opens, and the compression in the head end Fuel in ection from the orifice f takes place early in the casing o stroke and the fully compressed charge is ignited by means of the sparking plug 0.

Any other means of ignition may be employed, and if desired the engine may operate on a Diesel or semi-Diesel cycle, the injection of fuel being in that case retarded "to the end of the compression stroke.

s on the opposite side of the crank pin conveyes the oil to the other bearing a and thence to a pipe a leading to a regulator t on the wall of the guide cylinder. The regulator is provided with an adjustable screw or needle-valve t which allows suitable flow of oil through the orifice i into the guide cylinder. The dummy piston a guid ing the cross-head i in the latter is formed with a central well a in which the oil collects, surplus oil escaping through holes a on to the gudgeon pin cross-head hear 'ing of the connecting rod is and finding its way through the crank case into the oil sump r. The boss below the gland 7' is arranged to enter the well a at the end of the up-stroke of the piston, thereby forcing oil through a passage 6 in the piston rod to radial ducts e delivering the oil to the outer periphery of the piston between the rings 6.

An oil-filler 0 is provided on the side of the crank case for the introduction of lubricant and an oil gauge may be fitted n any convenient position. k I I The crank axles m ma be provided with oil-throwers m to remove excess lubricant, which returns to the sump through suitable ducts. I V

A magneto '0 is shown mounted on a bracket e upon the crank case and drivenby chain or other gearing contained in the A screw 02 holds the magneto in position.

t will'be understood that the invention is not limited to the details of the construe tion described and illustrated by way of example. Thus the engine be provided wlth two or more cylinders, if desired.

Having thus describedfmv.invention, what it claim as such and desire-to secure by Letters Patent is 1. A two-stroke engine comprisinga cylinder, a piston reciprocable within said cylinder. one end of said cylinder forming the working chamber, the other end of said cylinder forming the pump chamber. an 'eX- haust valve in said working chamber, an inlet port in said pump chamber, a transfer port adjacent to said inlet port, a passage connecting said ports, means foradmitting air only through said' inlet port, and means for carburetting said air after compression in said pump chamber. I

2. A two-stroke engine comprising a cyl inder, a piston reciprocable within said cylinder, one end of said cylinder forming the working chamber, the other end of said cylinder forming the pump chamber, an exhaust-valve in said working chamber; an inlet port in said pump chamber, .a transfer port adjacent to'said inlet port, a passage connecting said ports, means for admitting aironly through said inlet port, said air being compressed, in said pump chamber and delivered through said passage and transfer port to the working side of said piston, and means for carburetting said air thereafter. V

A two-stroke engine. comprising a cylinder. a piston recipro-cablein said. cylinder, an exhaust valve in one end of said cylinder,

an inlet port in the opposite end of said cylinder, a transfer port adj acenttosaid inlet port, an inlet valve in external communication with both said ports, aninjection port in said cylinder, a reservoir for combustible liquid, a pump in communication with said reservoir and delivering to said injectioii' port, a needlevalve controlling the communication with said reservoir, and means for operating said pump to deli'verduring the movement of said piston towards the first end of said cylinder.

4. A two-stroke engine, comprising a cylinder, a piston reciprocable in said cylinder, an exhaust valve in one end of said cylinder, an inlet port in the opposite end of said cylinder, a transfer port adjacent to said inlet port, an inlet valve in external port, a chamber connecting said ports, an in let valve opening into said chamber, a crank shaft rotating in connection with the reciprocation of said piston...crank discs upon said crank shaft, said discs having lateral,

grooves to form cams, and valve tappets having their extremitiesv engaged in said cam-grooves, said tappets operating said exhaust and inlet valves.

6. A two-stroke engine comprising a cylinder. a piston reciprocable in said cylinder, an exhaust valve in one end of said cylinder,

an inlet port in the opposite end of said cylinder, a transfer port adjacent to said inlet port, a chamber connecting said ports,'an inlet valve opening into said chamber, a crank shaft rotating in connection'with the reciprocation of said piston, crank {discs upoiisaid crank shaft, said discs having grooves on their outer side faces to form cams, and valve tappetshaving their ex-.-

tremities engaged in'said cam groovessaid tappets being positively connected to said exhaust and inlet valves respectively and controlling said valves in both directions byv the rotation of said'cam discs.

7. A two-stroke engine, comprising a cylinder, a piston reciprocablein'said cylinder,

an exhaust valve in one end of said cylinder,

an inlet port inthe opposite end of said cylinder," a transfer port adjacent to said inlet port, a chamber connecting said port's,

an inlet valve opening into said chamber. meansfor injecting combustible into said cylinder, a crankshaft rotating in unison with the reciprocation of said piston, crank disks upon said crank shaft, having lateral grooves to form cams, and posit ve means operated by the rotation of said cam-discs for controlling said exhaust and inlet valves and injecting means. v

8. A twostroke engine, comprising a cylinder, a piston reciprocable in said cylinder, an exhaust valve in one end of said cylinder, an inlet port in the, oppositeend of said cylinder, a transfer port adjacent to said inlet port, a chamber connecting saidports. an inlet valve opening into said chamber, an injection port in said cylinder,

a reservoir for combustible, a fuel-pump in communication with said reservoir'and de livering to said injection-port, a ported barrel to said pump, said barrel admitting combustible through a port from said reservoir, a valve controlling the opening of said port,

haust and inlet valves and fuel-pump.

9. A two-stroke engine, comprising a working cylinder, a working piston recipro cable in said cylinder, an exhaust. valve in the head end of said cylinder, an inlet port in the opposite end of said'cylinder, a transfer port adjacent to said inlet port and in"v external communication therewith, anexter- V nal chamber connecting said portsfan inlet valve in said chamber, a guide-cylinder in,

alignment with said working cylinder, a

cover separating said working and guidecylinders, a: dummy piston 'reciprocable in said guide-cylinder, a piston-rod connecting said working and dummy pistons, said pis ton-rod passing through said cylinder cover. a packing gland for said-'piston-rod iii said cylinder cover, a crankshaft, a connecting rod between said dummy piston and crankshaft, cani-discs upon said crankshaft, posi tive means operated by the rotation of said. cam-discs for controlling said exhaust and and means for positively operating said ex inlet valves, an eccentric upon said crankshaft, an oil-pump operated by the rotation of said eccentric and supplying lubricant to said crankshaft and guidecylinder, means for regulating the supply of lubricant to said guide-cylinder, means for collecting lu bricant upon said dummy piston, oil-ways through said piston-rod and working piston, and means for forcing lubricant collected by said dummy piston through said oil-ways.

10. A two-stroke engine comprisinga cyl inder. a shallow piston reciprocable in said cylinder, one end of said cylinder vtorming the working chamber, said piston having a smooth surface on the side towards said chamber, the other end of said cylinder being of the same diameter the first and forming the pump chamber, a mechanically operated exhaust valve in said working chamber, an inlet port in said pump chamher, a transfer port adjacent to said inlet port, said ports separated by a distance equal to the depth of said shallow piston, a passage connecting said ports externally of said cylinder, and a mechanically operated inlet valve in said passage, said transfer lens port delivering a charge from said pump chamber into said working chamber across the smooth surface of said. piston.

11. A. two-stroke engine, comprising a cylinder, a. shallow piston reciprocable in said cylinder, a hollow piston rod, a mechanically operated exhaust valve at the head end of said cylinder, an inlet port at the opposite end of said cylinder, a transfer port adjacent to said inlet port, said ports separated by a distance equal to the depth of said shallow piston, an external chamber connecting said ports, mechanically operatedinlet Valve in said external chamber, radial oil-ways connecting the periphery of said piston tothe bore of said hollow piston rod, and means operated by the reciprocation of said piston to force lubricant through said hollow piston rod and radial oilwa-ys.

In testimony whereof I aiiix my signature in presence of two Witnesses.

RICHARD HARLAND DICKINSON.

Witnesses:

VIo'roR F. FEENY, GYPIL J. 

